The primary research goals of this laboratory have been the biological and biochemical characterization of the new human papovaviruses, BKV and JCV. Although much has been learned about BKV, little is understood about JCV due primarily to difficulties in propagating the virus in readily available cells. Efforts have therefore been directed toward obtaining a suitable system for JCV growth, and we have achieved some success in propagating the virus in human amnion cells. Further efforts are being made to increase the yields. Since both human papoviruses cause persistent infection in their hosts, we have attempted to study BKV persistence in cell culture. A system of persistent infection in human fetal brain cells was successfully established and the mechanisms of viral persistence were studied. The persistently infected cells are phenotypically transformed, but possess properties which are unique; they lack T-antigen and viral DNA is present in all cells in the form of episomal DNA. These cells thus provide new insights into mechanisms of viral persistence and transformation.